Bug 19724: Add timestamp to biblio_metadata and deletedbiblio_metadata

Bug 19724: Add timestamp to biblio_metadata and deletedbiblio_metadata

Since bug 17196, biblioitems.timestamp is not always updated after a
change in the MARC record.
We need to know the last modification time of the MARC record for some
features (like OAI-PMH parameters 'from' and 'until' for instance)

This patch only adds the missing column in biblio_metadata and
deletedbiblio_metadata

Test plan:
1. Run updatedatabase.pl
2. Verify that both tables have the new column, its value should be the
   greatest timestamp value from the corresponding biblio and
   biblioitems table entries
   You can verify with the following SQL query:
     SELECT b.biblionumber, b.timestamp as biblio_ts,
     bi.timestamp as biblioitems_ts, m.timestamp as biblio_metadata_ts
     FROM biblio_metadata m
     LEFT JOIN biblioitems bi ON (bi.biblionumber = m.biblionumber)
     LEFT JOIN biblio b ON (b.biblionumber = m.biblionumber);

Signed-off-by: David Bourgault <david.bourgault@inlibro.com>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druat <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>